Can a post-operative brace in slight hyperextension prevent extension deficit after anterior cruciate ligament reconstruction? A prospective randomised study

Abstract

It has been our observation that post-operative anterior cruciate ligament (ACL) braces together with the post-operative bandages do not always allow the knee to reach full extension. In ten uninjured knees with known hyperextension, the knees were bandaged in the same way as after an ACL-reconstruction. The knees were then studied radiologically in a Hypex brace set at 0 degrees, -5 degrees and -10 degrees of knee extension. Not a single knee was found to be straight in the brace set at 0 degrees. At -5 degrees most of the knees were straight or in slight hyperextension. It took -10 degrees to get all knees straight or in hyperextension. In a prospective randomised study 44 patients who underwent an arthroscopic ACL-reconstruction with a bone patellar tendon bone graft were randomised to use either a brace set at -5 degrees or a straight brace (0 degrees ) for at least the first three postoperative weeks. Before and three months after surgery range of motion was determined, using a goniometer with long arms, and sagittal knee laxity was measured with a KT-2000 arthrometer at manual max. Pre- and post-operative pain was evaluated with the Visual Analogue Scale (VAS). The same examiner (blindfolded to what type of brace was used) performed all the measurements. At three months, two of the 22 patients with the brace set at -5 degrees and twelve of the 22 patients with the straight brace had a loss of full extension of 2 degrees or more ( p<0.001). No significant differences were found between the groups in terms of knee flexion, sagittal knee laxity or post-operative pain. Although extension deficit after ACL-reconstruction can be prevented also in other ways, a Hypex brace set at -5 degrees seems to be an easy way of ensuring full knee extension.